Electronic chord selection device for a musical instrument

ABSTRACT

The 12 playing keys of an octave range on a standard keyboard each apply a set of chord tone signals to a chord modulator and the root and fifth parts also through input selection gates to a bass divider. Auxiliary controls or an automatic rhythm device drives the input selection gates to alternate the root and fifth parts in the bass and also drives the chord modulator and a bass keyer for various rhythmic patterns of chord and bass. A musical key selector picks any of six pairs of musical keys and controls the tone signals responsive to the playing keys so the chords produced are diatonic chords of the pair of selected musical keys. Other auxiliary controls allow the player to add or delete chord parts and to change the types of chords. Diode keyers feeding into current mixers allow multiple drives without introducing crosstalk and so minimize the number of keyers required.

United States Patent [72] Inventor Alfred B. Freeman 20418 Seaboard Road, Malibu, Calif. 90265 [21] Appl. No. 818,724

[22} Filed Apr. 23, 1969 [45] Patented June 29,1971

[54] ELECTRONIC CHORD SELECTION DEVICE FOR Primary Examiner-D. F. Duggan Assistant Examiner-Stanley .l. Witkowski Attorney-Hurvitz & Rose ABSTRACT: The 12 playing keys of an octave range on a standard keyboard each apply a set of chord tone signals to a chord modulator and the root and fifth parts also through input selection gates to a bass divider. Auxiliary controls or an automatic rhythm device drives the input selection gates to alternate the root and fifth parts in the bass and also drives the chord modulator and a bass keyer for various rhythmic patterns of chord and bass. A musical key selector picks any ofsix pairs of musical keys and controls the tone signals responsive to the playing keys so the chords produced are diatonic chords of the pair of selected musical keys. Other auxiliary controls allow the player to add or delete chord parts and to change the types of chords. Diode keyers feeding into current mixers allow multiple drives without introducing crosstalk and so minimize the number of keyers required.

Sara-craze CONTROL OUTPUT C/ECU/T PATENTED JUN29 1971 sum 1 er 2 kSbk kboRm OM RN NOWRQO QQKPHWM ELECTRONIC CHORD SELECTION DEVICE FOR BACKGROUND THE INVENTION 1. Field of the Invention The invention is directed to apparatus for playing chords and bass from single playing controls and for changing the chords produced by the controls to adapt for different musical keys.

2. Description of the Prior Art U.S. Pat. No. 2,645,968 to .I. M. I-lanert discloses apparatus for playing chords from a set of buttons and for bringing the root and fifth. parts of the chord out for alternate application to a bass divider. The large number of buttons to provide chords for all keys is confusing to the beginner and learning to play on the buttons does not assist learning to play in a more advanced manner on a standard instrument.

Another prior art device uses the playing keys of a standard keyboard to play chords in a special mode of operation. While somewhat more helpful in developing skills useful in normal playing, providing a sufficient number of chords for playing in all or even several musical keys imposes a distribution which complicates the chord playing for a beginner and defeats the original purpose.

SUMMARY OF THE INVENTION The invention provides apparatus for playing chords and bass from the playing keys of the standard keyboard or from a limited number of chord buttons. A musical key selector determines the set of chords produced in response to playing key or button operation and the sets provided are tailored to the particular musical keys. The beginner is thus faced with a limited number of playing keys or buttons but still has all the chords necessary to play in the key. A very economical musical key selecting means is a feature of the invention.

In the case of the standard keyboard, the chords from the playing keys have roots corresponding to the notes normally associated with the playing keys. The chords will be major or minordepending upon the position in the selected musical key so the player only has to pick the playing keys for the chord roots out with the left hand similarly to the way he picks the melody notes out with the right hand. Playing action for more advanced playing only requires that he operate more playing keys at a time to individually select the notes of the desired chords. The invention-also includes auxiliary controls which the player may operate to expand and change the chords produced by playing key operation beyond the diatonic set for the chosen musical key. Automatic rhythm means sounding root and fifth parts in the bass alternately and interupting the chord sounding rhythmically enhances the musical effects obtainable by a beginner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial block and partial schematic diagram of am embodiment ofthe invention.

FIG. 2 is a schematic diagram of several dual input keyers which might be used in the apparatus of FIG. 1. I

FIG. 3 is a partial block and partial schematic diagram of an alternative form of part of the apparatus of FIG. 1.

FIG. 4 is schematic diagram of another type of keyer which might be used with the apparatus of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The chord keying drivers are designated with the root notes of their respective chords n FIG. 1. Drivers 10 may consist of the playing keys of an octave range of a standard keyboard together with switches connecting positive voltage outputs to lines 11 whenever the respective playing keys are operated. The switches might be interlocked so only one of lines 11 would receive voltage at a time. The playing keys might be replaced with chord buttons or drivers 10 might consist of other devices such as the bass keying drivers shown in my copending US. Pat. application Ser. No. 748,245 of a Bass Playing System dated July 29, 1968. These bass keying drivers include interlocking means so only one operates at a time.

Each line 11 from a driver 10 goes to two of keyers 12, one of keyers 13, two of keyers 14, one of resistors 15, and a contact of musical key selector switch 16. The keyers 12 control signals for notes which are the minor third and third parts of the chord, the keyer 13 the seventh part and the keyers 14 the root and fifth parts. The two alternate sets of keyers 12 connect to busses l7 and 18, respectively, keyers l3 connect to bus 19, and the two alternate sets of keyers l4 connect to busses 20 and 21. Resistors 15 are also grouped in two alternate sets connecting to busses 22 and 23, respectively.

Busses 17 and 18 connect through alternate musical key switch 24 to selector control 25 which inhibits one and passes the signal on the other to mixer and modulator 27. With switch 24 in the position shown, selector control 25 changes the inhibit from bus 18 to bus 17 when it receives a control voltage on the line form mode switch 26. With mode switch 26 in the position shown, the control input comes through resistors 28 from the poles of musical key selector switch 16. With switch 16 also in the position shown, selector control 25 receives a positive voltage input through mode switch 26 only when drivers 10 for one of the notes C, A, F sharp, or D sharp are operated.

Mixer and modulator 27 thus receives signals from bus 18 when drivers 10 for notes C, A, F sharp, and D sharp are operated and from bus 17 when drivers 10 for the remaining notes are operated. With the just described control of busses 17 and 18, drivers 10 for the notes or'roots of C, C sharp, F, F sharp, G, and B will provide outputs from selector control 25 for the notes which are the third parts of the respective chords. Drivers 10 for the remaining notes D, D sharp, E, G sharp, A, and A sharp will provide notes which are the minor third parts of the respective chords. It will be recognized that these notes, when combined with the root and fifth parts in each case, will provide the major and minor chords of the diatonic sets for the musical keys of C and F sharp. If alternate musical key switch 24 is placed in its other position, busses l8 and 17 are reversed to selector control 25 and the thirds and minor thirds are likewise reversed. The chords provided with the root and fifth parts would then be for the musical keys of A and D sharp.

When musical key selector switch 16 is placed in its second position, resistors 28 connect to drivers 10 for the roots G, E, C sharp, and A sharp. The proper selection of thirds and minor thirds is then provided for the musical keys of E and A sharp for the shown position of switch 24 and for the musical keys of C sharp and G for the other position. The third position of switch 16 similarly provides for the musical keys of D and G sharp for the shown position of switch 24 and the musical keys of F and B in the other. If mode switch 26 is placed in its second position, selector control 25 is connected to bus 22 and will receive control voltage for inhibit reversal on operation of drivers 10 for the notes C, D, F sharp G sharp, and A sharp. This inhibits all minor thirds when switch 24 is in its shown position. If switch 24 is placed in its other position, all thirds will be inhibited. Placing mode switch 26 in its third position connects selector control 25 to bus 23 and reverses the third and minor third positions for switch 24.

Seventh switch 29 connects bus 19 to mixer and modulator 27 when operated. This causes the seventh parts to be included in the output of mixer and modulator 27 which also receives the root and fifth parts from busses 20 and 21 connecting to the outputs of keyers 14. Operation of drivers 10 thus produces signal outputs from mixer and modulator 27 which are either major or minor chords with sevenths if switch 29 is closed. If mode switch 26 is in its first position, the settings of switches 24 and I6 determine which drivers 10 will produce major chords and which minor. The set of chords always includes the major and minor chords making up the g diatonic sets for two different musical keys. The six combinations of positions of switches 16 and 24 provide for all of the 12 musical keys in six pairs.

It will be noted that change of the position of switch 24 changes majors to minor and minors to major. All major and minor chords can thus be obtained from any setting of the other controls merely by changing switch 24 which can be a push to change foot switch or similar device which can be operated conveniently by the player. With switch 26 in its first position, diatonic chords of the selected musical keys would be obtained without further action. Player operation of switch 24 would make all other major and minor chords available. With switch 26 in position two or three, all chords would be either major or minor and changing position of switch 24 or changing switch 26 between positions two and three would reverse them. Switch 29 should also be convenient for player operation so the seventh parts can be included or deleted as desired.

Busses 20 and 21 also connect through resistors 30 and 31 and resistors 32 and 33, respectively, to bass circuit 34. Diodes 35 and 36 connect the junctions of the resistor pairs to opposite outputs of flip-flop 37 so the signal from one or the other of busses 20 and 21 will be clamped andthe other will be effective to bass circuit 34. Bass circuit 34 includes one or more frequency dividers to produce an output which is one or more octaves lower than the input and which becomes the bass part. Control busses 22 and 23 connect to opposite inputs of flip-flop 37 to set it to pass the root part whenever a driver first operates. It will be noted that busses 22 and 23 connect-to alternate drivers 10 as do keyers 14 to busses and 21 to obtain this result,

Automatic rhythm device 38 also drives flip-flop 37 to alternate positions to alternately apply clamping voltages to diodes 35 and 36 and so pass the root and fifth parts alternately to the frequency dividers of bass circuit 34. Bass circuit 34 includes a keyer or modulator which responds to the input from rhythm device 38 to pass the output bass signal with a percussion envelop. Rhythm device 38 further drives mixer and modulator 27 to apply rhythmic modulations on the chord parts for further accompaniment to the bass part patterns. The outputs of mixer and modulator 27 and bass circuit 34 go to output circuit 39 which will include an amplifier for driving sound transducer 40 and may include tone forming circuits and controls.

Keyers 13 may be of any suitable type which passes its respective tone signal while receiving a positive control voltage input, Diode keyers of this type are widely used in present day electronic organs. Keyers 12 and 14 must be responsive to control voltage inputs from two different sources for keying their respective tone signals. FIG, 2 shows a type of keyer for keyers 12 associated with the drivers 10 for C and C sharp which is suitable for all keyers l2 and 14 and for keyers 13 as well. Each line 11 is connected to ground through a small decoupling resistor 41 and to as many drive resistors 42 as keyers 12, 13, and 14 as are associated with it. Drive resistors 42 go to the junctions of back to back diodes 43 and 44 connected between the respective outputs of tone generators 45 and busses 17 and 18, Busses 17 and 18 go to the bases of transistors 46 with collector load resistors 47 and bias and feedback resistors 48 which function as current mixers, The small voltage swing on the bases of transistors 46 and at the junction of diodesj 43 and 44 is further reduced by decoupling resistors 41 so there i no appr ci bl cro lk tween riv rs 0 sharing key rs. i

In he arrangement of FIG, 3, keyers 51 replace keyers 12, Y13 and .14 for h function of providing h r p r s in h cornpanirnent rangee Key r 1 m y r m y n e d in combination with k y 1 for ey ng root and fi Part in the b ss as in FIG. 1. Each keyer 1 l k y t r p ctive not in each of several oc ave lo ion out n c blc 2 to and modul o in re pon to con ro inputs from any of a number of driv rs 1 r ei a. c ble 53. Ea

keyer 51 receives control inputs via its cable 53 from the same drivers 10 as do all the keyers 12, 13 and 14 for the same note in the arrangement of FIG. 1. Line 11 for the driver 10 for C is shown going to keyers 51 for the notes C, D sharp, E, G, and A sharp. Connections from other drivers 10, while not shown, would be in the same pattern.

Busses 56, 57, and 58 provide inputs to each of keyers 51 to inhibit their response to particular control inputs from drivers 10. Busses 56 and 57 inhibit the inputs to keyers 51 which are to operate them for theminor third and third parts, respectively. Busses 56 and 57 are controlled from alternate musical key switch 24 and selector control 25 like busses 17 and 18 were controlled in the apparatus of FIG. 1. Bus 58 inhibits inputs for the seventh parts except when ungrounded by operation of seventh switch 29. With musical key selection switches 59 and 60 in their shown positions, lines 11 for the notes C, F, G, C sharp, F sharp, and B connect through resistors 61 and mode switch 26 to selector control 25. The chords for those drivers 10 will then be major or minor depending upon the position of alternate key switch 24 while the chords for the remaining drivers will be minor or major, respectively. Selector control 25 grounds one side for inhibiting when receiving and input and the other side when not receiving an input.

Placing mode switch 26 in its other position removes any input signal from selector control 25 so one input remains grounded. All chords will then be either major or minor depending upon the position of alternate key switch 24. Change of position of switch 59 changes C sharp and G to E and A sharp for connection through resistors 61. This changes the chord sets from those for the musical keys of C and F sharp to F and B for one position of switch 24 and from the musical keys of A and D sharp to D and G sharp. Change of position of switch 60 changes F and B to D and G sharp to provide the sets of chords for the remaining four musical keys of G and C sharp and E and A sharp. Switches 59 and 60 will not be changed to their other positions at the same time.

FIG. 4 shows a possible embodiment for the keyer 51 for the note C in which lines 11 for drivers 10 for the notes C and F are connected by resistors 62 to the base of transistor 65. Lines 11 for the notes D, G sharp and A also connect to the base of transistor through resistors 62 and 63 while diodes 54 from the junctions of resistors 62 and 63 connect, respectively, to buses 58, 57, and 56. It will be recognized that C is the seventh of D, the third of G sharp, and the minor of third of A. A positive voltage on the respective lines 11 causes transistor 65 to conduct unless the respective junction is clamped by the respective bus 56, 57, or 58 being held at ground potential. Resistor 66 connects the collector of transistor 65 to the base of transistor 67 so it will also be turned on by conduction of transistor 65 Transistor 67 in turn drives a set of keyers 68 for the note C in several different octave locations. It will be recognized that a transistor might be saved by reversing the input polarity or the polarity required for the keyers 68. It will further be recognized that this type of drive might be applied to keying systems such as those shown in my copending US Pat. application Ser. No. 783,205 for an Automatic Harmony Apparatus."

I claim:

1. In an electronic organ,

an array of playing keys encompassing an octave of notes of the musical scale,

a plurality of tine signal sources arranged in the order of the musical scale and including said octave of notes,

, a first bus, f a second bus,

a first plurality of electronic gates each responsive to actuation of a selected one of said playing keys for passing a tone signal to said first bus which is an nth part of the note pertaining to that one of said playing keys,

a further plurality of electronic gates each responsive to actuation of selected one of said playing keys for passing to said second bus a tone signal which is a mth part of the note pertaining to that one of said keys where n and m .are chordal components,

an output load, a twocondition selector for at will transferring tone signal from either one of said buses to said output load to the ei'tcluslon of tone signal from the other of said busses, and means responsive to actuation of selected ones of said playing keys to the exclusion of the others of said playing keys for selecting the condition of said two condition selector, wherein said nth part and said mth part are selected from at least one of 1. third and minor third parts and 2. fifth and root parts, of the notes represented by the actuated playing key.

2. The combination according to claim 1, wherein is further provided means for calling forth said fifth and root parts in a rhythmic pattern.

3, The combination according to claim 1, wherein is included a mode switch having three positions,

means for developing a control voltage according to the position of said mode switch in response to actuation of any one of four selected keys which are different for each of said positions of said mode switch, and

means responsive to said control voltage for actuating said selector.

4. in an electronic organ,

a sequence of playing keys encompassing an octave of musical notes,

means responsive to actuation of any one of said playing keys for generating tone signals representative simultaneously of a major and of a minor chord appropriate to that playing key,

means responsive to the identity of that playing key for automatically selecting those tone signals appropriate to only that one of said major and minor chords which is appropriate to that playing key,

an output transducer, and

means for applying the selected tone signals to said output transducer.

5. The combination according to claim 4, wherein said means for generating tone signals includes tone signal sources and control voltage responsive electronic gates connected in series between said sources and said output transducer, and

wherein said means responsive to said playing keys includes means for applying said control voltage selectively to said electronic gates.

6. A chord organ, comprising an octave of keys representing the roots of chords,

means responsive to actuation of each of said keys for generating a control voltage representing that key,

a plurality of tone signal sources,

a control voltage responsive normally nonconductive diode gate in series with each of said sources,

an output load comprising an acoustic transducer responsive to tone signal from said sources passed by said gates in response to said control voltages,

means connecting each of said control voltages to control a series of gates representing a group of chordal tone signals, said last named tone signals being appropriate to both a major and minor musical chord simultaneously, and

means for selectively inhibiting that one of the tone signals of each of said groups which determines whether said musical key shall be major or minor.

7. The combination according to claim 6, wherein is further included means for selectively including and excluding a seventh chord component in and from each of said groups.

8. The combination according to claim 6, wherein is further included means for selectively including in each of said groups either a fifth or a root chord component.

9. The combination according to claim 6, wherein is further included means responsive to actuation of four selected ones of said keys for controlling said means for inhibiting.

10. The combination according to claim 6, wherein is further provided means for selecting which of said four keys shall effect said controlling of said means for inhibiting.

.11. The combination according to claim 6, wherein is included means for rhythmically alternating tonal components of said chordal tone signals to form alternately constituted chords in rhythm.

12. The combination according to claim 6, wherein said tonal components are said fifth and root components. 

1. In an electronic organ, an array of playing keys encompassing an octave of notes of the musical scale, a plurality of tine signal sources arranged in the order of the musical scale and including said octave of notes, a first bus, a second bus, a first plurality of electronic gates each responsive to actuation of a selected one of said playing keys for passing a tone signal to said first bus which is an nth part of the note pertaining to that one of said playing keys, a further plurality of electronic gates each responsive to actuation of selected one of said playing keys for passing to said second bus a tone signal which is a mth part of the note pertaining to that one of said keys where n and m are chordal components, an output load, a two condition selector for at will transferring tone signal from either one of said buses to said output load to the exclusion of tone signal from the other of said busses, and means responsive to actuation of selected ones of said playing keys to the exclusion of the others of said playing keys for selecting the condition of said two condition selector, wherein said nth part and said mth part are selected from at least one of
 1. third and minor third parts and
 2. fifth and root parts, of the notes represented by the actuated playing key.
 2. The combination according to claim 1, wherein is further provided means for calling forth said fifth and root parts in a rhythmic pattern. 3, The combination according to claim 1, wherein is included a mode switch having three positions, means for developing a control voltage according to the position of said mode switch in response to actuation of any one of four selected keys which are different for each of said positions of said mode switch, and means responsive to said control voltage for actuating said selector.
 2. fifth and root parts, of the notes represented by the actuated playing key.
 4. in an electronic organ, a sequence of playing keys encompassing an octave of musical notes, means responsive to actuation of any one of said playing keys for generating tone signals representative simultaneously of a major and of a minor chord appropriate to that playing key, means responsive to the identity of that playing key for automatically selecting those tone signals appropriate to only that one of said major and minor chords which is appropriate to that playing key, an output transducer, and means for applying the selected tone signals to said output transducer.
 5. The combination according to claim 4, wherein said means for generating tone signals includes tone signal sourCes and control voltage responsive electronic gates connected in series between said sources and said output transducer, and wherein said means responsive to said playing keys includes means for applying said control voltage selectively to said electronic gates.
 6. A chord organ, comprising an octave of keys representing the roots of chords, means responsive to actuation of each of said keys for generating a control voltage representing that key, a plurality of tone signal sources, a control voltage responsive normally nonconductive diode gate in series with each of said sources, an output load comprising an acoustic transducer responsive to tone signal from said sources passed by said gates in response to said control voltages, means connecting each of said control voltages to control a series of gates representing a group of chordal tone signals, said last named tone signals being appropriate to both a major and minor musical chord simultaneously, and means for selectively inhibiting that one of the tone signals of each of said groups which determines whether said musical key shall be major or minor.
 7. The combination according to claim 6, wherein is further included means for selectively including and excluding a seventh chord component in and from each of said groups.
 8. The combination according to claim 6, wherein is further included means for selectively including in each of said groups either a fifth or a root chord component.
 9. The combination according to claim 6, wherein is further included means responsive to actuation of four selected ones of said keys for controlling said means for inhibiting.
 10. The combination according to claim 6, wherein is further provided means for selecting which of said four keys shall effect said controlling of said means for inhibiting.
 11. The combination according to claim 6, wherein is included means for rhythmically alternating tonal components of said chordal tone signals to form alternately constituted chords in rhythm.
 12. The combination according to claim 6, wherein said tonal components are said fifth and root components. 